The present invention is directed to aqueous ink compositions and ink jet printing processes. More specifically, the present invention is directed to aqueous ink compositions particularly suitable for the production of high quality images on print substrates. The ink compositions for the present invention reduce intercolor bleed and enhance optical density. The present invention is also directed to multicolor ink jet printing processes for the production of high quality images on print substrates. One embodiment of the present invention is directed to a set of inks for printing multicolor images in an ink jet printer, said ink set comprising (A) a first ink having a first color and comprising water and a colorant selected from the group consisting of (1) anionic dyes, (2) dyes having physically or chemically associated therewith a stabilizing agent having anionic groups thereon, (3) pigment particles having anionic groups chemically attached thereto, (4) pigment particles having physically or chemically associated therewith a stabilizing agent having anionic groups thereon, and (5) mixtures thereof; and (B) a second ink comprising water, an optional colorant having a color other than the first color, and an ammonium salt having at least two cationic ammonium functional groups, wherein the colorant in the first ink is capable of being immobilized on a printing substrate by interaction with the ammonium salt having at least two cationic ammonium functional groups in the second ink, thereby enabling reduced intercolor bleed.
Ink jet printing is a non-impact printing method which produces droplets of ink that are deposited on a print substrate in response to electronic digital data signals. Ink jet systems generally are of two types: continuous stream and drop-on-demand. In continuous stream ink jet systems, ink is ejected in a continuous stream under pressure through at least one orifice or nozzle. The stream of ink is periodically perturbed by pressure regulation in accordance with digital signals, causing it to break up into droplets at a fixed distance from the nozzle. At the break-up point, the charged ink droplets pass through an electrical field which adjusts the trajectory of each ink droplet to direct it to a gutter for ink circulation or to a specific location on a print substrate to produce an image. In a drop-on-demand system, an ink droplet is expelled from a nozzle directly onto a print substrate in accordance with digital data signals. Generally, a droplet is not formed or expelled unless it is to be placed on a print substrate.
Drop-on-demand systems are simpler than continuous stream systems since they do not require ink recovery, charging, or deflection. There are three types of drop-on-demand ink jet systems. One type of drop-on-demand system has an ink-filled channel or passageway having a nozzle on one end and a piezoelectric transducer near the other end to produce pressure pulses according to digital data signals. Multiple ink nozzles are used to deliver ink droplets onto a print substrate in an imagewise fashion. Several printheads and inks are used in a multicolor piezoelectric ink jet printing system. High resolution images can be obtained with this system. Examples of this system include the Epson 600 and 800 ink jet printers.
Another type of drop-on-demand ink jet printing system is called acoustic ink jet printing, which can be operated at high frequency and high resolution. Acoustic ink jet printing uses a focused acoustic beam formed with a spherical lens illuminated by a plane wave of sound created by a piezoelectric transducer. The focused beam reflected from a surface exerts a pressure onto the surface of the liquid ink, resulting in ejection of small droplets of ink onto a print substrate. An array of nozzles and corresponding transducers are used in an acoustic ink jet printing process to produce images on a print substrate in an imagewise fashion. Different types and configurations of acoustic printheads and substrate arrangements are possible. In a multicolor ink jet printing process, several acoustic ink jet printheads are used to deliver different inks onto a print substrate. Aqueous inks can be used in this drop-on-demand acoustic ink jet printing system. Examples of acoustic ink jet printing systems are disclosed in, for example K. A. Krause, "Focusing Ink Jet Head," IBM Technical Disclosure Bulletin, Vol 16, No. 4, September 1973, pp. 1168-1170, and in, for example, U.S. Pat. No. 4,308,547, U.S. Pat. No. 4,697,195, U.S. Pat. No. 5,028,937, U.S. Pat. No. 5,041,849, U.S. Pat. No. 4,751,529, U.S. Pat. No. 4,751,530, U.S. Pat. No. 4,751,534, U.S. Pat. No. 4,801,953, and U.S. Pat. No. 4,797,693, the disclosures of each of which are totally incorporated herein by reference. The use of focused acoustic beams to eject droplets of controlled diameter and velocity from a free-liquid surface is also described in J. Appl. Phys., vol. 65, no. 9 (May 1, 1989) and references therein, the disclosure of which is totally incorporated herein by reference.
Another type of drop-on-demand printing system is thermal ink jet printing. Thermal or bubble jet drop-on-demand ink jet printers have found broad applications as output for personal computers in the office and in the home. In thermal ink jet printing processes, the printhead typically comprises one or more ink jet ejectors, as disclosed in, for example, U.S. Pat. No. 4,601,777, U.S. Pat. No. 4,532,530, U.S. Pat. No. 4,412,224, U.S. Pat. No. 4,410,899, U.S. Pat. No. 4,251,824, U.S. Pat. No. 4,532,530, U.S. Pat. No. 4,601,777, U.S. Pat. No. 4,840,674, U.S. Pat. No. 5,145,518, U.S. Pat. No. 5,281,261, and U.S. Pat. No. 5,531,818, the disclosures of each of which are totally incorporated herein by reference. Each ejector includes a channel communicating with an ink supply chamber, or manifold, at one end and an opening at the opposite end, referred to as a nozzle. A thermal energy generator, usually a resistor, is located in each of the channels at a predetermined distance from the nozzles. The resistors are individually addressed with a current pulse to vaporize the ink momentarily within the respective channel to form a bubble that expels an ink droplet. As the bubble grows, the ink rapidly bulges from the nozzle and is momentarily contained by the surface tension of the ink as a meniscus. This phenomenon is temporary, and the ink is quickly propelled toward a print substrate. As the bubble begins to collapse, the ink still in the channel between the nozzle and the bubble starts to move towards the collapsing bubble, causing a volumetric contraction of the ink at the nozzle and resulting in the separation from the nozzle of the bulging ink as a droplet. The acceleration of the ink out of the nozzle while the bubble is growing provides the momentum and velocity for propelling the ink droplet in a substantially straight direction toward a print substrate, such as a piece of paper. Important properties of the ink in this context include viscosity and surface tension. Because the droplet of ink is emitted only when the resistor is actuated, thermal ink jet printing is a drop-on-demand system.
In a drop-on-demand ink jet printing apparatus, the printhead typically comprises a linear array of ejectors, and the printhead (with or without partition) is moved relative to the surface of the print substrate, either by moving the print substrate relative to a stationary printhead, or vice-versa, or both. In some apparatus, a relatively small printhead moves across a print substrate numerous times in swaths (i.e., multiple passes) to print a desired image. In this instance, the desired image is produced completely on a print substrate in several swaths before the substrate is advanced. This type of printing is called multi-pass (multiple pass) or checkerboard ink jet printing. In checkerboard ink jet printing (or multiple pass), the printhead passes over the print substrate and provides ink at desired locations (for example, printing only even or odd numbered dots in a swath). On one or more subsequent passes, the remaining dots in the image are printed before the print substrate is advanced. Multiple ink jet printheads and ink cartridges can be used to produce multiple color images on a print substrate. Alternatively, a printhead can be partitioned into several sections (for example, three small sections including cyan, magenta, and yellow inks) and equipped with different ink chambers, ink storage media, and inks in a multicolor ink jet printing system. These multicolor systems are commonly employed in desktop ink jet printers, including thermal ink jet printers. They produce good multicolor images on plain paper, but at a slower printing speed. Slightly higher printing speed can be achieved, however, by increasing ink jetting frequency and printhead sweeping rate.
Alternatively, a stationary ink jet printhead that consists of an array of ejectors and extends the full width of a print substrate can pass ink down the print substrate to give full page images, in what is known as a "full width array" ink jet printer. When the printhead and the print substrate are moved relative to each other, imagewise digital data is used to activate the thermal energy generators or resistors selectively in the printhead over time so that the desired image can be created quickly on the print substrate in a single pass mode. The full width array printhead is generally preferred to be in a stationary position while the print substrate is continuously moving to receive inks as it passes through the printhead or printheads. The full width array printhead or printheads can also, however, be moved across the print substrate if desired. In a multicolor ink jet printing process, several full width array printheads, including cyan, magenta, yellow, and black printheads, as well as other optional printheads and their corresponding inks, can be used to provide different colored images on the print substrate at a high speed. Fast ink jet printing can be achieved by using the full width array printheads.
In a multicolor ink jet printing process, several inks can be printed on a print substrate. In some instances two different inks can be printed next to each other. Intercolor bleed can occur if the inks are not dried properly or if the printing process is too fast for the ink set. Undesired ink mixing on a print substrate, especially on the surface of a plain paper, can cause severely distorted images near the border of two inks. After ink drying, the border of the two inks shows irregular structure with poor edge sharpness (or raggedness) because of the invasion of one ink into the other. The bleed images are not desirable and can be detected easily by eyes. This phenomenon is called intercolor bleed or color bleed. Intercolor bleed occurs particularly when a darker ink (such as a black ink) and a lighter ink (such as a yellow ink, a cyan ink, magenta ink, or the like) are printed next to each other, because of high contrast between the two colors. Intercolor bleed can also occur when two color inks are printed next to each other (for example, a yellow ink next to a magenta ink, a yellow ink next to a cyan ink, a magenta ink next to a cyan ink, or the like). The severity of the intercolor bleed generally is affected by ink type and composition, absorption rate of the printed substrate, printhead design, ink drop mass, ink dot size, and method and speed of printing. There is a need to reduce intercolor bleed and to produce high quality multicolor ink jet images on print substrates, including plain and coated papers, transparencies, textiles, and other desired substrates.
U.S. Pat. No. 5,091,005 (Mueller et al.), the disclosure of which is totally incorporated herein by reference, discloses inks comprising, by weight, from about 4% to about 10% formamide, from about 1% to about 10% dye, and the balance water when printed on paper from an ink jet printer have improved resistance to bleed, especially when printed at a rate up to about 3.7 kHz.
U.S. Pat. No. 5,116,409 (Moffatt), the disclosure of which is totally incorporated herein by reference, discloses the alleviation of color bleed (the invasion of one color into another on the surface of the print medium) using ink jet inks by employing zwitterionic surfactants (pH-sensitive or pH-insensitive) or ionic or nonionic amphiphiles. The inks comprise a vehicle and a dye. The vehicle typically comprises a low viscosity, high boiling point solvent, one or two amphiphiles at concentrations above their critical micelle concentration (cmc), while the dye typically comprises any of the dyes commonly employed in ink jet printing. The amount of surfactant/amphiphile is described in terms of its critical micelle concentration (cmc), which is a unique value for each amphiphile. Above the cmc, micelles form, which attract the dye molecule and thus control the color bleed. Below the cmc, there is no micelle formation, and thus no control of the color bleed.
U.S. Pat. No. 5,106,416 (Moffatt et al.), the disclosure of which is totally incorporated herein by reference, discloses the alleviation of color bleed (the invasion of one color into another on the surface of the print medium) using ink jet inks by employing zwitterionic surfactants (pH-sensitive or pH-insensitive) or ionic or non ionic amphiphiles. The inks of the invention comprise a vehicle and a cationic dye. The vehicle typically comprises a low viscosity, high boiling point solvent, one or two amphiphiles at concentrations above their critical micelle concentration (cmc), while the dye typically comprises any of the dyes commonly employed in ink jet printing. The amount of surfactant/amphiphile is described in terms of its critical micelle concentration (cmc), which is a unique value for each amphiphile. Above the cmc, micelles form, which attract the dye molecule and thus control the color bleed. Below the cmc, there is no micelle formation, and thus no control of the color bleed.
U.S. Pat. No. 5,133,803 (Moffatt), the disclosure of which is totally incorporated herein by reference, discloses the control of color bleed (the invasion of one color into another on the surface of the print medium) using ink jet inks by employing high molecular weight colloids, such as alginates, in conjunction with amphoteric surfactants and/or nonionic amphiphiles. The inks disclosed comprise a vehicle and a dye. The vehicle typically comprises a low viscosity, high boiling point solvent and one or two surfactants at concentrations above their critical micelle concentration (cmc), while the dye typically comprises any of the dyes commonly employed in ink jet printing. The amount of surfactant is described in terms of its critical micelle concentration (cmc), which is a unique value for each surfactant system. Above the cmc, colloidal species form, which attract the dye molecules and thus control the color bleed. Below the cmc, there is no colloid, and thus poor control of the color bleed results. Also, the presence of the high molecular weight colloid further improves the text print quality and renders sharper definition among colors printed adjacent one another.
U.S. Pat. No. 5,181,045 (Shields et al.), the disclosure of which is totally incorporated herein by reference, discloses certain dyes which become insoluble under specific and well defined pH conditions. By forcing a dye to become insoluble on the page, migration of the dye is inhibited, thereby helping to reduce bleed between inks of different colors. The dye is forced out of solution from the ink by contact with another ink having the appropriate pH (either higher or lower than that of the first ink).
U.S. Pat. No. 5,320,668 (Shields et al.), the disclosure of which is totally incorporated herein by reference, discloses certain colorants which become insoluble under specific and well defined pH conditions. By forcing a colorant to become insoluble on the page, migration of the colorant is inhibited, thereby helping to reduce bleed between inks of different colors. The colorant is forced out of solution from the ink by contact with another ink having the appropriate pH (either higher or lower than that of the first ink). In particular, an ink containing a colorant comprising a pigment in combination with a pH sensitive dispersant is used in conjunction with an ink of the appropriate pH.
U.S. Pat. No. 5,342,440 (Wickramanayake), the disclosure of which is totally incorporated herein by reference, discloses water insoluble black dyes which are formulated in a microemulsion based ink. When printed adjacent to color inks (yellow, magenta, cyan) containing water soluble dyes, bleed does not occur between the black and the color dyes.
U.S. Pat. No. 5,476,540 (Shields et al.), the disclosure of which is totally incorporated herein by reference, discloses a method for controlling color bleed between adjacent multicolor ink regions on a print medium. Color bleed involves the migration of color agents between adjacent zones in a multicolored printed image on a print medium. A first composition containing a gel forming species and a color agent is brought into contact on a region of the print medium with a second composition having a color agent and a gel initiating species or chemical conditions which bring about gelation. In alternative embodiments, the print medium can be pretreated with either a gel initiating species or a gel forming species (with no colorant), followed by treatment with a gel forming species or gel initiating species (with colorant), respectively. The formation of the gel upon the print medium impedes the movement of the color agent or agents and thus reduces the color bleed between adjacent zones.
U.S. Pat. No. 5,531,817 (Shields et al.), the disclosure of which is totally incorporated herein by reference, discloses the control of color bleed (the invasion of one color into another on the surface of the print medium) using ink jet inks by employing either high molecular weight polymers that exhibit a reversible gelling nature with heat or certain amine oxide surfactants that undergo sol-gel transitions. The inks further include a vehicle and a dye. The vehicle typically comprises a low viscosity, high boiling point solvent and water. Certain high molecular weight polymers, under the correct solution conditions, can form gels which can be subsequently melted by heating of the gel. When the melted gel is cooled, it will then reform into a gel. The viscosity of an ink employing such a gel can be reduced to a viscosity low enough to permit jetting from the print cartridge. After leaving the print cartridge, the melted gel will again reform into a highly viscous gel to immobilize the droplet of ink and prevent its migration on the media. Therefore, two drops of different colors, when printed next to one another will thus be inhibited from migrating or bleeding into one another.
U.S. Pat. No. 5,565,022 (Wickramanayake), the disclosure of which is totally incorporated herein by reference, discloses ink jet ink compositions which exhibit fast dry times and bleed free prints when printed onto a print medium so that the throughput of an ink jet printer can be increased. The ink compositions comprise (a) at least one dye; (b) at least one high boiling, water insoluble organic compound; (c) at least one amphiphile; and (d) water. The dye can be either water soluble or water insoluble and the high boiling organic compound has a vapor pressure low enough such that only water evaporates from the ink during normal printing operations. The amphiphile is present in an amount sufficient to solubilize the water insoluble organic compound in the water. Preferably, the amphiphile belongs to a class of compounds known as hydrotropes.
U.S. Pat. No. 5,198,023 (Stoffel), the disclosure of which is totally incorporated herein by reference, discloses an ink set in which bleed between yellow and black inks is reduced by using a cationic yellow dye in the yellow ink and an anionic dye in the black ink. Bleed is further reduced by adding a multivalent precipitating agent to the yellow ink. With regard to bleed between yellow and other color inks (cyan and magenta), bleed is reduced by also employing anionic dyes in the color inks.
U.S. Pat. No. 5,428,383 (Shields et al.) and U.S. Pat. No. 5,488,402 (Shields et al.), the disclosures of each of which are totally incorporated herein by reference, disclose a method for controlling color bleed in multicolor thermal inkjet printing systems. Color bleed involves the migration of coloring agents between adjacent zones in a multicolor printed image on a substrate. To control color bleed between any two ink compositions in a multi-ink system, at least one of the ink compositions will contain a precipitating agent (such as a multivalent metal salt). The precipitating agent is designed to react with the coloring agent in the other ink composition of concern. As a result, when the two ink compositions come in contact, a precipitate is formed from the coloring agent in the other ink composition which prevents migration thereof and color bleed problems. This technique is applicable to printing systems containing two or more ink compositions, and enables distinct multicolor images to be produced without the problems normally caused by color bleed.
U.S. Pat. No. 5,518,534 (Pearlstine et al.), the disclosure of which is totally incorporated herein by reference, discloses an ink set for alleviating bleed in multicolor printed elements employing a first ink and a second ink, each containing an aqueous carrier medium and a colorant; the colorant in the first ink being a pigment dispersion and the second ink containing a salt of an organic acid or mineral acid having a solubility of at least 10 parts in 100 parts of water at 25.degree. C.
U.S. Pat. No. 5,250,107 (Bares), the disclosure of which is totally incorporated herein by reference, discloses a water-fast ink composition and method for making the same. A selected chemical dye having at least one functional group with an extractable hydrogen atom thereon (such as --COOH, --NH.sub.2, or --OH) is combined with an ammonium zirconium polymer salt (such as ammonium zirconium carbonate, ammonium zirconium acetate, ammonium zirconium sulfate, ammonium zirconium phosphate, and ammonium zirconium oxalate). The resulting mixture preferably contains about 0.01-5.0% by weight ammonium zirconium polymer salt and about 0.5-5.0% by weight chemical dye. Upon dehydration of the mixture, the ammonium zirconium polymer salt and chemical dye form a cross-linked dye complex which is stable and water-fast. The mixture can be dispensed onto a variety of substrates (e.g. paper) using thermal inkjet or other printing systems.
U.S. Pat. No. 4,267,088 (Kempf), the disclosure of which is totally incorporated herein by reference, discloses coatings particularly useful as marking inks in which an epichlorohydrin-modified polyethyleneimine and an ethylene oxide-modified polyethyleneimine cooperate in aqueous solution to form a composition capable of application to form deposits adherent to most materials and resistant to most organic solvents but readily removable by water.
U.S. Pat. No. 4,197,135 (Bailey et al.), the disclosure of which is totally incorporated herein by reference, discloses an ink for use in ink jet printers containing a water soluble dye and a polyamine containing 7 or more nitrogen atoms per molecule, with the ink composition having a pH of 8 or above, the upper pH limit being dye decomposition dependent. The ink has improved waterfastness over an equivalent ink formulation without the polyamine additive.
U.S. Pat. No. 4,659,382 (Kang), the disclosure of which is totally incorporated herein by reference, discloses an ink jet ink composition comprising a major amount of water, a hydroxyethylated polyethyleneimine polymer, and a dye component, wherein the polymer has incorporated therein from about 65 to about 80 percent by weight of hydroxyethyl groups.
U.S. Pat. No. 5,693,129 (Lin), the disclosure of which is totally incorporated herein by reference, discloses an ink jet ink composition which comprises water; a colorant selected from the group consisting of a dye, a pigment, and a mixture of a dye and pigment; and a material selected from the group consisting of (1) a hydroxyamide derivative having at least one hydroxyl group and at least one amide group; (2) a mercaptoamide derivative having at least one mercaptol group and at least one amide group; (3) a hydroxythioamide derivative having at least one hydroxyl group and at least one thioamide group; (4) a mercaptothioamide derivative having at least one mercaptol group and at least one thioamide group; (5) an oxyalkylene(alkyleneoxide) reaction product of the above said derivatives; (6) a thioalkylene(alkylenesulfide) reaction product of the above said derivatives; and (7) mixtures thereof. The inks comprising the said ink jet ink composition exhibit good latency especially in a high resolution thermal ink jet printhead (for example, 600 spi) and can be printed onto a print substrate either with or without heat for the drying to give excellent images with reduced curl and cockle.
Japanese Patent publication 57-198768, the disclosure of which is totally incorporated herein by reference, discloses a type of water-base ink made of acidic dye and/or direct dye, cationic water-soluble resin, water-soluble organic solvent, and water.
Although some of the aforementioned references describe ink compositions for the reduction of intercolor bleed, a need remains for ink compositions suitable for high resolution and high speed ink jet printing. A major concern with all ink jet printers, and with high resolution ink jet printers in particular, is clogging of the nozzles during operation and between operations. This clogging is caused by evaporation of an organic solvent or water from the opening of the nozzle. In dye based inks, this evaporation can cause crystallization or precipitation of soluble ink components, such as dyes or solid additives, as well as causing an increase in ink viscosity. In pigment based inks, this evaporation can cause precipitation of the pigment particles because of flocculation or aggregation, or precipitation of solid additives, as well as causing an increase in ink viscosity. Initial evaporation of water and solvent generally causes an increase in ink viscosity, which affects the ability of the heater or resistor of a printhead to fire a drop of ink properly through the nozzle.
Accordingly, a desirable characteristic of ink jet inks is the ability of the ink to remain in a fluid and jettable condition in a printhead opening that is exposed to air. The maximum idling time that still allows a printhead to jet a first drop of ink with a transit time of 100 microseconds or less wherein the ink travels a distance of 0.5 millimeters after a period of nonuse or idling is called the latency (1st drop) or decapped time. The maximum idling time that still allows a printhead to jet a 9th drop of ink with a transit time of 100 microseconds or less wherein the ink travels a distance of 0.5 millimeters after a period of nonuse or idling is called the 9th drop latency or decapped time. This test is run with the printhead or nozzles uncovered or decapped and generally at a relative humidity of 15 percent. The time interval is the longest period of time that the printhead, uncovered, will still fire a specified drop (1st drop or 9th drop) without a failure. The longer the latency (1st drop latency or 9th drop latency) time rating, the more desirable is the ink for use in an ink jet printer.
The inception of clogging can also cause distortion of the image or alphanumeric characters being printed by the printhead. This distortion can appear as a drop of ink that is displaced from its intended position. Sometimes two drops of ink will be formed equally spaced from the intended target position. Misplacement of the ink drops can also lead to intercolor bleed and poor image quality as a result of the undesired mixing of two color inks in a multicolor ink jet printing process. Intercolor bleed occurs particularly near the border areas of two colors. Sometimes small numerous satellite drops are also produced. On some occasions the drop can even reach its intended position but at a lower drop volume or drop mass and produce a lower optical density image. Ultimately, the clogged nozzle can fail to fire entirely, and no image can be generated on a print substrate, resulting in an image defect.
With the demand for higher resolution printers, the nozzles of printheads in ink jet printers are correspondingly decreasing in size. Nozzle openings of a printhead are typically about 50 to 80 microns in width or diameter for a 300 spots per inch (300 spi) resolution printhead. With the advent of higher resolution (for example, 360 spi, 400 spi, 600 spi, 720 spi, and the like) printheads, these nozzle openings are even smaller, and are typically about 10 to about 49 microns in width or diameter. These printheads with small nozzle dimensions can require special inks that do not easily clog the small nozzle openings.
Some antibleed ink compositions comprising gel-like materials or multivalent metal salts in combination with certain incompatible colorants can have difficulty in jetting effectively through the small nozzles of a high resolution printhead. Thus, a need remains for ink jet ink compositions that not only enable reduced intercolor bleed, but also exhibit the ability to be used in a high resolution printhead.
In a high speed ink jet printer, inks preferably are able to print at a high frequency, preferably at least 4 KiloHertz. Inks containing high molecular weight materials can have high viscosity and are not particularly suitable for fast ink jet printing. In addition, inks with high viscosity tend to have even higher viscosity upon water and solvent evaporation (due to idling), which results in short ink latency, poor ink jettability, and slow refill. Such inks may not be suitable for high speed ink jet printing. Antibleed inks that can function in a high resolution printhead with a high frequency response are desirable because they allow the inks to be printed at a high speed with good throughput and good print quality. There is also a need for the development of ink jet ink compositions that exhibit low viscosity with good jettability and refill characteristic in addition to the ability to reduce intercolor bleed.
Accordingly, while known compositions and processes are suitable for their intended purposes, a need remains for improved multicolor thermal ink jet printing processes. In addition, a need remains for multicolor thermal ink jet printing processes wherein the prints generated exhibit reduced intercolor bleed. Further, a need remains for multicolor thermal ink jet printing processes wherein the prints generated exhibit excellent image quality. Additionally, a need remains for multicolor thermal ink jet printing processes with rapid printing times. There is also a need for multicolor thermal ink jet printing processes wherein the prints generated exhibit improved optical density of the black and/or color image areas. In addition, there is a need for multicolor thermal ink jet printing processes which employ materials, software, and hardware of low cost. Further, there is a need for multicolor thermal ink jet printing processes which enable reduced kogation. Additionally, there is a need for multicolor thermal ink jet printing processes which can be used in conjunction with microwave drying of the prints. A need also remains for multicolor thermal ink jet printing processes wherein the prints generated exhibit improved waterfastness. In addition, a need remains for multicolor thermal ink jet printing processes wherein the prints generated exhibit improved lightfastness. Further, a need remains for multicolor thermal ink jet printing processes wherein the inks exhibit good latency and maintainability. Additionally, a need remains for multicolor thermal ink jet printing processes wherein the images generate have good to excellent color quality.